Accumulator



June 11, 1946. w OVERBEKE 2,401,792

ACCUMULATOR Filed Jan. 12, 1944 Patented June 11, 1946 ACCUMULATOR John William Overbeke, New York, N. Y., anignor to Simmonds Aerocessories, Inc. of New York. New York, N. Y., a corporation of New York Application January 12, 1944, Serial No. 517,939

2 Claims. 1

This invention relates to pressure accumulators or surge relievers of the kind used on aircraft, boats, and other installations to store or cushion a pressure fluid.

General objects of the invention are to provide a pressure accumulator of improved construction leading to better functioning during service, particularly where the installation is subject to violent bodily movement while in use, as is the case with accumulators used in aircraft or small boat hydraulic pressure systems,

The accumulators generally used in such systems comprise a strong pressure shell which is divided into two fluid chambers by a flexible membrane, one chamber being charged with compressible air under pressure, and the other being ported to the liquid pressure system. This liquid, usually oil, partly fills the shell during normal use, one typical arrangement in current use providing a 600 p. s. i. pressure in the air chamber when the membrane is fully expanded and there is no oil in the shell, which is increased to a normal storage pressure of 1500 p. s. i. by the introduction of hydraulic system liquid sumcient to increase the compression of the air to that extent. The membrane of course must be able to adapt itself to the various air volumes encountered over the extreme range of pressures used. In a well designed accumulator it is desirable that the membrane be capable of expelling and thus utilizing all or substantially all of the liquid from the shell while yet maintaining a decided pressure in the line and at the same time be capable of collapsing or invaginating sufflciently to enclose an air chamber having a third or less of the original volume. To this end the membrane must have considerable fullness, or elasticity, or both, and in present designs these membranes range from rubber diaphragms fastened at the middle of the shell and having corrugations to impart suflicient fullness, on up to very full bag-like membranes which are fastened at one end of the shell and are adapted to be everted or invaginated between fully expanded and fully compressed positions. The bag-like form allows use of a stronger and simpler shell which may be of one piece seamless or else of welded construction. Both the full diaphragm and the bag-like forms of membranes, and especially the latter, with their contained air, tend to float around in the liquid within the shell, and when the accumulator is tumbled about as when in an aircraft, or small boat, the buoyed membrane tends to twist, turn, and tug at its fastened edges, in a manner that harmfully creases and wears it and, more seriously. may

even interfere with its proper expansion and eversion during use.

With such difliculties in view, objects of the invention are to provide an accumulator wherein the available shell volume is efficiently utilized to displace a maximum amount of oil between the fully expanded and the compressed positions of the membrane, and wherein the membrane itself is anchored against undue floating and twisting about within the shell.

More particular objects of the invention are to provide an accumulator having a membrane of bag-like form which has its edges firmly attached and sealed near one end of the accumulator shell, and is except for this one opening at its mouth of closed, non-apertured air and liquid impervious form, wherein the shell is equipped with means for anchoring the otherwise free end of the membrane.

A further object of the invention is to provide a membrane for pressure accumulators which has a new and useful form and shape adapting it to be sealed and anchored in accordance with the principles of the invention.

Other objects of thev invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplifled in the construction hereinafter set forth, and

the scope of which invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. l is a central vertical sectional view through an accumulator embodying features of the invention; and

Fig. 2 is a fragmentary horizontal sectional view along line 22 of Fig. 1.

Referring more particularly to the drawing, there shown an accumulator having a shell lo which may be of any suitable shape or type, being illustrated as having a seamless spherical form. Within the shell is a membrane i I of special configuration dividing the shell into an air compartment l2 and an oil compartment l3. The membrane is of rubber or rubber-like elastic material and, in the illustrated embodiment, is of generally bag-like form terminating in an open mouth, the edges ll of which are molded for attachment to a closure unit at the air introducing end of the shell.

This closure and bag holding unit is more fully described and specifically claimed in my copending application, Serial No..515,933, filedv Dec. 28, 1943, and its features are shown and generically claimed in my copending application Serial No. 516,167, filed Dec. 29, 1943. As here shown the closure comprises a thickened mouth or neck l5 on the shell within which a collar it having a relatively constricted central opening is slidably fitted. A segmented locking ring il prevents outward movement of the collar and is fitted within a suitable annular groove on the inside of the mouth IS. A stopper l8-is slidably fitted for outward movement within the constricted central opening of the collar l6 and has at its lowerend a flange l9 having a stepped upper'surface underlying the lower face of the collar III which may be suitably grooved a illustrated to accommo wardly through the collar to at least a limited extent. An air passage 20 goes through the stopper 18 and has a back check valve 2| fitted at its outer end and a perforate membrane excluding plate 22 at its inner end.

A lock-nut 23 prevents the stopper from dropping inwardly through the collar and a holding ring 24 seats over the shell mouth and is pinned to the collar to prevent the latter from dropping inwardly from the locking ring II. If wanted,

, the holding ring 24 may be arrested by such looking ring I! rather than by the shell mouth itself.

At the other end of the shell there is a liquid passing opening 25 within which an oil plug 26 is fitted and welded or otherwise suitably attached. This plug has an enlarged base 21 which is insertable through the wide mouth at the other end of the shell. A liquid passage 28 extends through the plug and is threaded or otherwise suitably prepared at its outer end for attachment with the tubing of a hydraulic pressure system.

Extending upwardly from the plug base 21 is a post 29 which may be of various forms and shapes but is here illustrated as of generally tapered tubular construction formed of bent per- 1 forate sheet metal of the kind used in strainers, filters, and the like.

The outer walls of this post are braced by interior webs 30 which are ing application Serial No. 515,932, filed Dec. 28,

1943,'and the features of such a plug having an interior support are described and claimed in my copending application, Serial No. 515,934, filed Dec.28, 1943. These copending cases, however, do not have the membrane anchoring features characteristic of the present invention.

The button 3| provides a more or less cene trally disposed anchor for the otherwise free end of the membrane ll. As illustrated. the walls of this membrane descend, when in inert condition, from its attached edges l4 downwardly toward and almost to the plug end of the shell where they are everted or invaginated back toward the central shell area and toward the anchoring button 31. The central portion 22 of the bag is molded so as to be fitted and preferably snapped over the button 3i and to grip the latter tightly outwardly from the constricted neck 32. If desired a separate rubber band (not shown) may be snapped over this constricted post portion to help hold the bag on the anchors ing button, or the membrane portion 32 may be suitably cemented to such button.

The anchoring button is preferably disposed somewhat beyond the center of the shell away from the liquid introducing end and may be arranged up to and more of the distance away from the oil plug end of the shell so as to hold the lower end of the bag readily when the latter is in compressed condition under service. As shown, the membrane substantially occupies a major part of the available space within the shell interior when in inert condition and is sufilciently elastic to be expanded so as to occupy all of the shell interior except the reasonably small space occupied by the post 29. This anchoring of the otherwise free and unattached end of the membrane controls its floating and twisting action while the accumulator is moving about and tests show a very high efllciency in emptying the oil from the shell interior, indicating that oil is not.

\ form illustrated and preferably used but may be shown as being of similar perforate sheet metal suitably welded or soldered in place. Such brace or the entire posthowever, may be of cast framing or of any other suitable construction cape- 3 3| here shown as being in the form of a generally rounded hollow casing which is welded or soldered to the sheet metal portion of the post,

the entire post assembly being of relatively constricted diameter at 32 where this joint occurs. The perforations or orifices in the walls and interior support of the post 29 are adapted to pass oil from the compartment B to the passage 28, and their aggregate liquid passing capacity well exceeds the capacity of such passage, assuring an unrestricted fiow of oil in and out of the shell during use. Some general principles of such an oil plug having an enlarged head insertable through a wide mouth at the opposite end of the shell and bearing a wall or plate of considerable area enabling the provision of an adequate number of oil passing of the full diaphragm type having its edges attached at or near the middle of the shell interior and the post may be of, any suitable shape and form so long asit provides an anchoring button or other anchoring means within the interior of the shell in position to control movement of the otherwise freeunattached part of. the membrane or diaphragm. The anchor post for example need not be made part of the oil plug although this has obvious advantages and is preferred at present.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter 01 language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. An accumulator having an air compartment and an oil compartment, a flexible membrane separating said compartments, a post extending into said 011 compartment toward said membrane and having its end attached to the central part of said membrane to hold the latter, said membrane having its edges attached within said shell in a vicinity remote from the base of said post,

and means for-passing oil through said post and in and out of said shell.

2. An accumulator having an air compartment and an oil compartment, a flexible membrane separating said compartments, a hollow post of perforate sheet metal extending into said oil compartment and having a button at its terminal end, said membrane having its central part fixedly seated over said button, and means for passing 10 oil from said hollow post in and out of said shell.

' JOHN WILLIAM OVERBEKE. 

